Consciousness
and
Quantum Mechanics

In this accessible narrative essay, we take a journey with 20th century physicists beyond the
limits of old world views to explore the fascinating world
of quantum mechanics and its profound philosophical
implications. The world described by quantum mechanics is strange
and counter-intuitive, undermining the notions of materialism,
determinism, and separation. We also explore the measurement problem
in quantum mechanics and examine arguments why consciousness is needed
to fully resolve the problem. Such resolutions, however, force us to
radical alterations in our understanding of both the world and consciousness.

New Worlds

In 1492 Columbus set sail on a journey to unknown lands,
pushing the limits of human experience and knowledge. It was
the beginning of the Renaissance, and the beginning of a
revolution in thought that would give birth to modern
science, a vessel that would carry Newton beyond the earth
itself.

Four hundred years later the earth was mapped, lands were
colonized and Columbus was a legend. The earthly realm was
no longer a mystery. But by this time science had gone far
ahead. It had mapped the planets, stars, and galaxies. It
had revealed the laws of nature—both on earth and beyond.
And people had put the knowledge into practice, transforming
the lives of everyone it touched. The universe was no longer
a mystery, but an intricate lawful machine.

Yet, at the dawn of the 20th century, while civilization was
transforming under the influence of this Newtonian vision, a
few adventurous souls were being guided by another vision
which would take them to an unknown frontier, beyond the
limits of Newton's universe.
These would be the future pioneers of a strange new world, a
wonderland that defied common sense. But no one could then
imagine what profound implications this revolution would
have. Not even the pioneers themselves could foresee the
depth of mystery before them as they took the first few steps
on the journey through the quantum realm.

Two Heroes

Werner Heisenberg, the first revolutionary physicist to
abandon the classical Newtonian universe and break
trail into the quantum realm, compared his journey with that
of Columbus. The greatest achievement in his discovery of
America was not the idea to sail around the world or his
careful preparation for the trip. No, Heisenberg says, "his
most remarkable feat was the decision to leave the known
regions of the world and to sail westward, far beyond the
point from which his provisions could have got him back home
again." And so it is with science, Heisenberg continues, "it
is impossible to open up new territory unless one is prepared
to leave the safe anchorage of established doctrine and run
the risk of a hazardous leap forward."

Young and daring, Heisenberg took the first quantum leap with
his abstract matrix mechanics in 1925. These strange laws
formed the first consistent theory of the
atoms whose behavior defied explanation within Newton's
universe. Like Columbus, Heisenberg had discovered a new
world. But he hadn't found it alone. . .

Only a few months after young Heisenberg had set foot on the
new land, an older fellow appeared on the horizon, having
found the same frontier by a different route. It was Erwin
Schrödinger, who had found his way to the quantum realm with
a theory of wave mechanics. Being the older of the two,
Schrödinger had traveled with more caution and vision.

Both had dared. And both survived the dangers, discovering
by two different paths the same new frontier of scientific
exploration.

Overthrowing The Old Order

Neither Heisenberg nor Schrödinger could fully anticipate in
those early days just how much their discoveries would change
the Newtonian world back home. The wonders that this quantum
realm revealed would soon challenge the materialism that had been the basis for the Newtonian
universe. As one crossed the border into the quantum realm,
materialism seemed to evaporate. Thus, just as the pioneers of
Columbus' time could return home with word that the world was
not flat, our quantum pioneers would bring us word that the
world is not ultimately comprehensible in terms of material objects.
Regarding the assumption of
materialism, Schrödinger comments, "anyone who wants to make
it can do so; it is convenient, if somewhat naive. He will
be missing a great deal if he does." Or, as Heisenberg put
it, "materialism rested upon the illusion that the kind of
existence, the direct "actuality" of the world around us, can
be extrapolated into the atomic range." And he adds a
warning that "the naive materialistic way of thinking is an
obstacle to understanding the quantum concept of reality."

Despite the profound discoveries of Heisenberg and
Schrödinger over sixty years ago, most of us today still
think we live in the naive materialistic world. Like the ancient Greek philosopher
Democritus, we think that the fundamental substance of the
universe is composed of indivisible and indestructible atoms
which move in empty space. From the complex arrangements
and motions of these basic particles of matter, all other
things are derived. As Democritus put it, "A thing merely
appears to have color, it merely appears to be sweet or
bitter. Only atoms and empty space have a real existence."
This
ancient seed of materialism came to dominate the modern
Western worldview.

In the 1680s Isaac Newton formulated his mathematical laws of
universal motion, throwing the scientific revolution into
full swing. Newton's laws united the motion of objects in
heaven and earth—both the moon and an apple moved according
to the same laws he discovered. With their mathematical
precision, it seemed that nothing could not be described by
these universal laws. Thus the conception grew that the
universe was made of material objects which moved in space
according to these laws of Newton, like a big cosmic
clockwork. So, in this grand vision, everything could be
reduced to the lawful motion of material bodies. And since these laws
made predictions with mathematical certainty, the cosmic
machine was totally determined—there was no freedom.
Furthermore, this world existed objectively, independent of
our observation. Thus, in addition to materialism, the world
view of classical physics was characterized by determinism
and objectivity.

This classical mechanism was the old universe which
Heisenberg and Schrödinger would abandon in search of a new
frontier. But what prompted them to leave? The powerful
laws of Newton had explained everything from the motion of
the planets to the motion of baseballs. It had given people
incredible machines and engines, tools and instruments. But
as the 20th century drew closer, and classical physics
extended its investigations into the small world of those
fundamental atoms, nature began to defy Newtonian explanation. Experimental
results no longer agreed with the predictions of Newton's theory.

Just as circumnavigation established the reality of a globe
behind the illusion of a flat earth, the discovery of quantum
mechanics revealed a strange new reality beneath the illusion
of material objects. While it may be convenient to assume a flat or
material world, were we to expand our range of experience, we
would find limits to these notions. Similarly, beyond the physics of Newton we find that reality is not a
big machine after all, even though it seems to be. The door has been opened to a new frontier.

The Quantum Reality Behind The Veil of Classical
Mechanism

What has the quantum realm revealed beneath the illusion of
Newton's universe?

That determinism, which rigidly governed Newton's
universe like a cosmic machine, cracks open to admit spontaneity.

That the objective world, existing "out there"
independent of measurement, vanishes, leaving a
world in which the properties of phenomena depend upon how
we choose to measure them.

That the manifold world of separate independent
objects interacting locally within space and time is
transcended, revealing a realm of nonlocal connection.

As strange as this new quantum world may seem, it is not off
in some far land—it is here and now, hidden beneath the veil
of materialism. And one does not need a particle accelerator
to get to the quantum realm any more than one needs a boat to
get to a round earth—it is already here, the true nature of
this apparently flat world. We already live in this quantum
wonderland. So let us take a look at our true home.

We Are Such Stuff As Dreams Are Made On: As Matter
Dissolves

The first piece of the Newtonian mechanism to crumble was
materialism: the immutable atoms were not so immutable after
all. Soon after the discovery of radioactivity in 1896 it
was found that atoms sometimes transmute into other atoms,
just as the alchemists had dreamed. Next, the electron was
discovered in 1897, a particle much smaller than any of the
supposedly fundamental atoms. Thus, the atoms forming the
substantial basis for all existence in the material world
view were not the firm foundation they were taken to be. But
this discovery in itself only pushed materialism down one
step in scale, to the smaller sub-atomic particles which made up the
atoms. While the substantial foundation of matter had shifted, it was
still just as firm. . .or so they thought.

Thus, at the dawn of the 20th century, the physicists of a
new generation were faced with a new realm to explore. Since
atoms were no longer fundamental entities, it was now the task of these 20th
century physicists to discover the true elementary particles, how they combine to form the atoms,
and the laws governing those atomic systems. It was at this
point, however, that Newton's classical laws began to fail.
Attempts to explain the structure and behavior of atoms using the classical
laws simply gave the wrong answers. For example, in 1911
Rutherford in England proposed a planetary model of the atom,
in which a collection of negatively charged electrons orbited a
positively charged nucleus, just as planets orbit the sun.
But the known laws predicted that any electronic charge
moving in an orbit must radiate energy. Consequently, as they lost energy to radiation, the orbiting
electrons would spiral into the nucleus, in much the
same way that a satellite falls out of orbit, losing energy
due to its drag in the earth's atmosphere. In the case of
the electrons in an atom, however, they would fall out of orbit very
quickly, resulting in an almost instant collapse of the whole atomic structure—catastrophe. But the plain fact was that the
atomic orbits were stable, and classical physics simply could
not explain this fact.

To add to the troubles, Max Planck proposed in 1900 that
atoms absorbed and radiated energy only in specific discrete quantities.
According to Newton's laws, atoms could exchange energy in arbitrary amounts. But this did not explain the observed
spectrum of radiation from atoms. To produce the observed spectrum, Planck proposed that energy
in atoms was like quantities of money: instead of coming
in any amount, it must always come in collections of a smallest quantity,
called quanta. The quantum of money in the U.S., for
example, is the cent. And the quantum of action in the
universe is now called Planck's constant. When he made his hypothesis, there was no
explanation for this strange quantization of atoms, and yet
there was no way around it. This quantum, which Planck
called "the mysterious ambassador from the real world," was
then revealing the first of many paradoxes of the quantum
world.

To help remedy the situation, a young
Danish student of Rutherford made a quite radical proposal.
His name was Niels Bohr, and he was to become the father of
the quantum revolution. Bohr used Planck's strange quantum
idea and proposed a bold model of the atom which explicitly
denied the validity of the old classical laws. Without
explaining why, Bohr simply assumed that there were only
certain stable electron orbits, so that the electrons could
orbit at some distances but not at any others. In addition,
when electrons "jump" from one orbit to another, a quantum of
light is emitted. From this simple model, Bohr was then able
to predict the observed atomic spectra, and offer a reason
why only certain wavelengths of light were emitted from atoms. But while Bohr broke
away from the classical laws of Newton, he did not find any
new fundamental laws to replace them. The physicists still could not
explain why Bohr's orbits were stable, or what the electrons
did during their jumps.

Before Heisenberg and Schrödinger could solve this atomic
puzzle and reveal the strange laws of the quantum, one last
piece was needed. One day, a French physicist
named Louis de Broglie was thinking about Einstein's
paradoxical proposal that light was composed of particles,
despite the fact that it was known to be a wave. Somehow,
light had both a wave aspect and a particle aspect. De Broglie then
had a brilliant insight that connected this paradox with
Bohr's atomic model in a new way: If light waves can have
particle properties, de Broglie thought, then material
particles ought to have wave properties. The particle-wave
duality should hold for matter and light alike. Using this
hypothesis, de Broglie explained why there were only certain
stable orbits in Bohr's model: If the electron is not just a particle but also a wave,
then only certain standing waves would be allowed around
the nucleus. Just as a plucked string on a stringed instrument plays
a specific fundamental tone and specific overtones, the standing wave of the electron can only
vibrate at certain frequencies. These frequencies of the electron wave, de Broglie proposed,
correspond to Bohr's stable orbits, with higher tones being
higher energy orbits. It was a brilliant proposal. Yet,
what does it mean to say that matter is a wave? Here we have
our first hint that the solid particles of Newton's universe
were to quickly dissolve.

Inspired by de Broglie's vision of matter waves, Schrödinger
set out to discover their laws. Just as light waves obey an
equation, these matter waves should have their own wave
equation, too. In 1925 he began to search, to find a path
into the quantum realm. After hitting a blind alley and
struggling for months, Schrödinger finally broke through,
discovering the now-famous Schrödinger wave equation.
Solving this equation for the case of the atom, Schrödinger
derived wave functions which corresponded to Bohr's
electronic orbital waves, thus placing atomic stability on
the solid basis of mathematical law. With this wave
mechanics, he had set a firm foot into the strange land of
the quantum.

Although both Heisenberg and Schrödinger embarked on their
historic journeys at about the same time, Heisenberg took a
short-cut, and arrived earlier. Instead of using de Broglie's
wave-pictures of the atomic orbits, he made a youthful plunge
from Bohr's model straight into the quantum realm.
Heisenberg put all the possible electron jumps of the atom
into a big table, called a matrix. He was then able to
discover the proper laws for these matrices, and directly set
foot into the quantum realm with this matrix mechanics. And
it was not long before Schrödinger proved that they had both
indeed arrived at the same discovery: the wave mechanics and
the matrix mechanics were mathematical variations of the same
quantum mechanics. It was 1926, and the new territory was
opened up.

Although quantum mechanics gave all the correct predictions, no one yet
really understood what it meant. While Heisenberg and
Schrödinger deserve the credit for giving quantum mechanics a
consistent mathematical basis, it was Niels Bohr who was to
tackle the conceptual problems of this new theory. Just what
were the "matter waves" described by the wave functions,
anyhow? Were material particles just "the foam on a wave of
radiation" as Schrödinger said? Or did matter rest on
nothing but the probabilities in Heisenberg's matrices?
Bohr's answer turned out to be a strange combination of
both: in a sense, the world is particles and in a sense, the
world is waves. The two views are complementary, neither one
by itself telling the whole story.

These waves of matter were not ordinary waves, however.
Waves of water or sound are vibrations of an underlying physical medium.
The quantum waves, however, are not vibrations of anything physical.
Matter had dissolved into a nonmaterial wave of probability, describing not
the actual physical properties of the particles, but only their
probable, or potential properties. So an atomic orbit is not an actual path followed by
a material particle, but rather a wave of possibility for the
particle to be found in different locations. And rather than describing the
movement of actual particles as Newton's laws did, the
quantum laws describe the movement of these waves potentiality.
The actual particles are gone—only their possibilities
remain. Thus the solid substance of materialism had
evaporated into wave functions, describing only the
probabilities for particles to appear.

And so it happened that the journey into the quantum realm
revealed that the apparent world of hard matter rested not on solid
material particles as Democritus envisioned, but on the
airy cloud of non-material probabilities. Materialism was
just a castle in the clouds, no less an illusion than the
flat earth.

Spontaneity In Nature: Does God Play Dice?

The overthrow of the material basis for the world was to be
only the beginning of the quantum revolution. Basing
physical reality on waves of potentiality was to
undermine other assumptions of the Newtonian universe as
well, and determinism was to be the next pillar of classical
physics to fall. The universal machine was no longer
predictable with absolute certainty. Now it had spontaneity.

In both quantum and classical physics, we begin
by choosing an isolated system to study. For example, we
might study the solar system, or a single atom, or perhaps
two billiard balls. By restricting our study to a specific
system like this, we define and simplify the problem, for it
would be just too complicated to consider the whole universe
at once.

In the case of classical physics, it was found that when the
systems got very small—about the size of an atom—then the
strict deterministic laws of Newton did not work anymore. So,
the domain of classical physics was found to be limited to
large systems, just as the domain of "flat earth" geometry is
limited to small areas. And just as "round earth" geometry
can explain everything that "flat earth" geometry explains
and more, the quantum physics, too, applies to both the large
systems and small atomic systems. It is more general and
more comprehensive than classical physics alone.

After choosing a system to study, the next step in describing the
world with physics is to determine the state of the system. In the case
of classical physics, the state is quite simple: the state at any given
moment is the set of positions and velocities of the objects in the system. If we are
considering the solar system, for example, then the state
would be given by the positions and velocities of all the
planets in their orbits. Likewise, the state of a system of
two billiard balls would be given by the position and
velocity of each ball. So for any given system, it can exist
in many different possible states: the two balls can be
close together and at rest, they can be far away and moving
quickly, one can be moving and the other at rest, and so on.
If, for the sake of simplicity, we consider just their positions in one dimension,
then every possible state of
the two billiard balls can be represented as a point in a
two-dimensional graph, plotting the position of one ball on
the x-axis and the position of the other ball on the y-axis.
So by just specifying a point on this graph, we know the state of our
system. We can call this the "state-point."

Given any initial state, the classical laws will then tell us
how the two balls will move in the future. Thus, the state-point
will move around on the plane of the graph, following a curve
corresponding to the state-points at each instant in time.
There are two important features of this movement: First, the movement of the state-point is
smooth and continuous: neither of the balls suddenly "jumps"
from one place to another, causing a break in the curve. This
means that once any state-point is known, the whole curve of
future and past state-points is totally determined. If we
know where the balls are now, we can predict with certainty
where they were or will be. Second, the state-point
represents the actual state of the system, the state that we
would observe were we to look. So when we observe the two
balls, we can directly observe the state, and this does not
change it at all. For example, if you were to look at the
two billiard balls, this observation would not change their
locations. In other words, the state accurately represents the
two balls both when they are observed as well as unobserved.

Now if our system is very small, this method of classical
physics no longer works and we must use the methods of
quantum mechanics. Let us take the example of an atom. As
we discussed earlier, it was found that the electrons have
only certain stable orbits, which are described by standing waves of potentiality
and not actual paths through space. So,
instead of describing the orbital state by the electron's
position, each of these orbits is represented by a wave
function, which is the mathematical description of the electron's possible positions when measured. Thus, since the
electron has no actual position, but only a potential
position, we cannot use the classical method of "state-
points" to describe its state. We must find another way.

With quantum mechanics we represent the state of a system by
the wave function. Let us illustrate with a simple example
how this wave function represents the potential properties of
the electron. Suppose our electron can potentially exist in
only two places: inside a box or outside a box. Now before
we look, the electron's state is described as not actually in the box or actually
out of the box, but only potentially in either position.
Now we can imagine that there might be
a large possibility for the electron to be in the box and
only a small possibility for the electron to be out of the
box, or vice versa, or perhaps the possibilities are about
equal. If we imagine a two-dimensional graph with the "inside box"
possibility on one axis and the "outside box" possibility on
the other axis, then the state can be represented as an arrow
pointing either more toward one axis or the other, depending
on which position is more probable. Thus our quantum state
can be thought of as an arrow, or vector, living in a
possibility space. In addition, this state-vector, as it is
called, points in a direction which determines the relative
potentialities of the system.

Now since the state-vector does not necessarily point
entirely along one axis but can have components along both
axes, the electron is not actually in the box or actually out
of the box. Rather, the electron is just potentially in or
out of the box, but not actually either. So the state
vector, or wave function, represents only a potentiality for
something to exist in a definite place.

We noticed earlier that Newton's equations moved the state-
point of the billiard balls around continuously in its actual
space. In a similar way, Schrödinger's equation moves this
state-vector around continuously in the possibility space.
So as time passes, the direction of the arrow may change,
meaning that the electron's potential for being in or out of
the box will also change. And, just as with the classical
state-point, this state-vector will continuously move around
in a completely determined way. But there is a radical
difference between what happens to the quantum state-vectors
and the classical state-points when we make a measurement.
In the classical case, we could directly measure the state of
the billiard balls without changing anything. But in that
case the state was not a mere potentiality: it already represented something actual.

In quantum mechanics the state-vector represents a potential
for something actual, rather than simply something actual.
But we cannot observe a merely potential position, for when we measure position,
we only measure an actual position in the box or out of the
box—never potentially both in and out of the box at the same
time. In quantum mechanics,
when a system is measured, the state changes from being a potential for
several things to actually being one thing. This
means that when the system is measured, the state vector must suddenly jump
so that it is pointing along just one axis or another, and
not somewhere in between. It is as if we could only see the
shadow of the potential state, as it is projected onto an
axis of actuality. Thus, the transition from potential to
actual is often called a projection.

One of the most remarkable features of this projection is
that the actual event which manifests in any given case is
determined only by probability. When the state becomes
actual, there is a sudden, discontinuous jump in the state
that has an element of true spontaneity to it. Although
deterministic laws still apply to the unobserved potentials,
when a measurement is made, and the electron manifests either in the box or
out of it, the result is unpredictable. It is not determined by the particular
circumstances surrounding the event but is truly spontaneous.
Which of the possibilities manifests upon measurement is not determined—even in principle.

Thus, in the quantum realm, the deterministic machine of Newton has
cracked open. No longer is the universe a giant cosmic
machine. While
there is a deterministic law in the quantum realm, it applies
only to the possibilities while the system is unobserved. When a
measurement is made, however, the potential is made
actual, breaking deterministic law and introducing
spontaneity into the world. There is no predicting which
state will become actual—only the probabilities are
determined. And so one more premise of the Newtonian
mechanism has been undermined. The cosmic machine is falling
apart, its matter dissolving into potentiality, its
determinism making room for freedom.

Nonseparability: Is Reality One or Many?

In Newton's mechanistic universe, not only was reality made
of matter which followed strict deterministic law, but it was
thought to be composed of many separate, independent material
particles. So far on our journey into the quantum realm, the
materialistic and deterministic assumptions have been
undermined. First, we found that the particles were not
substantial bits of solid matter
but rather waves of potentiality. Then we found that, while
these waves of potentiality themselves are determined, their
projection into actuality exhibits spontaneity. Next, we will
investigate whether this quantum world, like the classical
world, is really composed of separate, independently existing
entities. In other words, is this new world of potentiality
a "Many" or a "One"?

Let us, for the sake of simplicity, consider a system of just
two particles which have interacted with each other at some
point in the past. Suppose we have a box as before and each
particle can be either in the box or out of the box. Now
when we look, we will find one of four actual states: 1) both
in the box, 2) both out of the box, 3) one in the box and the other
out of it, and 4) vice versa. So our possibility space for the
system will have four directions, and the state of this two-particle system will be represented by a single state vector
pointing in some combination of the four directions. For
example, if the vector has a large component in the direction
where both particles are in the box, then the probability of
finding the particles in that actual state will be large.
But, so long as the vector has components in the other
directions as well, there is a possibility of finding one of
several actual states when we look. Thus, the state vector
represents a potential for the particles to be found in any
of the four possible states we can actually observe.

Now it is important to notice that the one state vector
describes the potentialities of both particles. So if one of the particles
is measured, the state vector for the whole
system will be projected. Thus, by measuring one of the
particles, the state of both is affected.

What is amazing about this is that the state of the other particle changes instantly—even if it is in another galaxy. One might
think at first that some strange faster-than-light communication
passes between the two particles when one is measured. But such
strange mechanisms are not at all necessary when we remember
that the two particles were not really separate in the first
place—the one state vector described the potentiality for
them both. Thus, in the world of potentiality, there were
not two particles at all, but just one potentiality which
contained the possibilities for measurements of them
both. And, since the potentiality exists in a possibility
space rather than a physical space, the "physical" distance
between the particles is irrelevant. Although they are
separated in spacetime, in the potential
world they are united as one. Thus, the
complementary wave-particle aspects of matter are accompanied
by their respective nonlocal-local aspects.

In this quantum world, things are interconnected beyond the
limits of space and time. Behind the classical world of
separate material particles lies a world that is
nonseparable. In essence, a system of two particles is not really
two separate particles at all, but one nonseparable potential
which contains the possibilities for the two
particles. Similarly, a system of many particles is also
united in the same way. Thus, the whole universe is united in
one cosmic wave of potentiality living in a vast space of
unimaginable possibility. While the world appears to be a
Many, quantum mechanics demonstrates that it is fundamentally a One.

The Loss Of Objectivity: Is The Moon There When
Nobody Looks?

As we explore further into the quantum realm, things only get
stranger. With the evaporation of matter, determinism,
and finally separability, our hero Schrödinger began to
get a bit worried, for as he looked further into the
unexplored territory, he saw some very odd things, indeed.
What was most disturbing to Schrödinger was the fact that
when an atom was not observed it could be in a
potential state and then—just by merely measuring it—
we somehow trigger the projection of the potential to the
actual. To illustrate just how odd this situation is,
Schrödinger imagined performing the following experiment with
a cat.

He envisioned a single radioactive atom which can
spontaneously decay, transforming into a different element.
So whenever we measure this atom, it will be in one of two
mutually exclusive actual states: decayed or not decayed.
(This is entirely analogous to the electron being actually in
or out of the box.) But if we do not measure the atom, then
its state vector can be potentially in both states, pointing
partly in the decayed direction and partly in the not-decayed
direction. Initially, of course, the atom was in the not-
decayed state, so the state vector pointed along the not-
decayed axis. But as Schrödinger waits, there is a larger
probability that he could find the atom decayed, so as time
passes the vector has a smaller component along the not-
decayed axis and a larger component on the decayed axis. But
the main point is that, so long as Schrödinger does not measure it,
the atom is not actually in one or the other states, but only
potentially decayed or not-decayed.

Now Schrödinger imagines putting the radioactive atom,
a detector, a hammer, a poison bottle into a cage with a cat
in it. Schrödinger arranges it all so that when the atom
decays, the detector will be triggered, causing the hammer to
break the poison bottle, releasing the poison and killing the
cat. Schrödinger closes the cage and waits a few minutes.
Now since the state of the cat is directly dependent on the
state of the bottle, which in turn is dependent on the state
of the atom, when Schrödinger opens the cage to observe the state, he will
see an actual live cat, if the atom is not decayed, or an
actual dead cat, if the atom is decayed.

But what is the state of the cat while the cage is closed?
In this case, we are forced to say that the cat is
in a state similar to that of the atom: it is not actually
dead or actually alive, but just in a state of being
potentially both dead and alive. While it may not seem so
strange to think of tiny atoms as having no actual state,
it seems ridiculous to think of a cat in this way. Can it be true that in the quantum realm even
cats can be in potential states? And can it be that just
because Schrödinger opens the cage, the potential state of the cat
suddenly becomes actual?

A classical physicist, not having ventured into the strange
quantum realm, would consider such ideas as nonsense: "It is
impossible for a cat to be in such a state!" But this
reaction is like a land-locked sailor considering a round
earth as nonsense: "It is impossible for my lake to be
round." Indeed, the roundness is very difficult to detect on
such a small scale. But a sailor with expanded horizons
would recognize the fact that the lake, like the earth upon
which it lies, must be slightly round. Similarly, while it is for all practical purposes impossible
to detect the strange quantum effects for large
objects such as cats, were we to expand our classical
horizons into the quantum realm, we would recognize the fact
that cats, like the atoms of which they are composed, can be
in potential states. Like it or not, this is how the world
really works beneath the illusion of classical mechanism,
beneath the illusion of a world actually "out there,"
independent of measurement.

This brings us to the second, more mysterious question: What
exactly transforms
the cat from a potential state to an actual state? What projects the state-vector
onto just one or the other of the axis states? A classical physicist, in an
attempt to retain the actual world of large objects,
might propose that the projection takes place when the system
"gets large," and can then be treated with the old classical
physics. But just how large? Two atoms, ten atoms, a
thousand? Making size determine projection is very
arbitrary. Moreover, this solution does not even make
sense, for if one or two atoms can be in a potential state,
then so can three or four, or fifty or five thousand—size is
a matter of degree, while actuality is not. Claiming that
the world suddenly becomes actual when the system gets "big
enough" is like our land-locked sailor claiming that when a
lake gets small enough, then suddenly it really becomes
perfectly flat. What he ought to say is that when the lake
gets small enough, it is as if it were really flat, while in
reality it is still slightly round. Similarly, when our system gets
big enough, it is as if it were really in an actual state,
while in reality it is still in a potential state. We must
be careful not to drag classical illusions
into the quantum reality.

So potential states do not suddenly, of themselves, become
actual when a system gets "large enough." But when do
they become actual? We still have not answered this
difficult question. In an attempt to solve this problem,
Eugene Wigner, one of the many physicists to explore the
newly discovered quantum realm, made a radical proposal.

Wigner began by taking the paradox of Schrödinger's cat one
step further. What would happen, he wondered, if he put another cage
around both Schrödinger and the first cage? Now Schrödinger
is in a new cage, and since Schrödinger's state is dependent on what he
sees when he looks at the cat, he is ultimately dependent on
the atom's state now as well. So as long as Wigner does not
open the big cage, Schrödinger will be in a potential
state just like the cat! The state vector will be in a
possibility space with the two directions: 1) "Schrödinger seeing
a live cat" and 2) "Schrödinger seeing a dead cat",
leaving poor Schrödinger suspended in potentia until Wigner
decides to open the larger cage. But now we can ask, What stops us from putting
Wigner and his cage in another, even bigger, cage? After
all, Wigner is made of atoms, too, just like Schrödinger and
the cat. So Wigner would then be in a potential state
too. By extension, we can see that, because there is noone outside the universe
to observe it, the whole world will be forever
in a potential state with nothing to project it into an
actual state. Is there a way to avoid such absurdity?

While it may be unusual for cats to be in potential states,
Wigner considered it intolerable for humans to be in such a
state. So to get out of this mess, Wigner proposed that the
projection happens with the involvement of nonphysical consciousness. When
Schrödinger opens the cage and looks at the cat, first his eye is
in a potential state, "eye with image of live cat" and
"eye with image of dead cat." Next, his brain is in a
potential state, "experiencing seeing a dead cat" and
"experiencing seeing a live cat." But it is at this point
that we cannot go any further, Wigner argued, for Schrödinger is only ever
conscious of one actual experience or another. And there
should be no doubt about this for him: it is an undeniable fact that anything
appearing in his consciousness is actually in one state or
another. When he looks at a cat it is always actually dead
or actually alive (or at least actually in some state or
another). Never is he conscious of a cat in a potential
combination of two mutually exclusive actual states. Thus, Wigner argued,
the potential must become actual when it appears in
Schrödinger's consciousness. Nothing physical—not the cat,
not the eye, not the brain—can project the state vector.
Only a nonphysical consciousness can do it. The buck stops
with consciousness.

Incredibly, in order to account for the actual existence of any unique and definite measurement result,
Wigner argues, we must recognize the existence of a
nonphysical consciousness. The world cannot be just a bunch
of inert matter, a collection of objects. There must also be
a subject, a consciousness, apart from objects, which is aware
of them. There is a similar argument in the context of classical physics. Just
consider the simple question, "how is it that I am seeing
anything at all?" Is there something like a little TV in
your head? But then who is watching it? And then how is it
that they see anything? By trying to account for the seeing
of anything with a brain or a TV or any other material
mechanism we are just adding more objects, and leaving the
question unanswered: what sees any of these objects at all?
One escape of this infinite regress is to recognize a subjective awareness apart from all
objects. Similarly, to account
for actual existence at all, we recognize a subject, or
consciousness, which—by its very nature—is not another
physical object in the system. So when any object is not in
your conscious awareness—an atom, a bottle, a cat, your own
body, a thought in your brain—it is (according to Wigner's interpretation of quantum mechanics) in a potential state.

What Wigner's interpretation proposes is that the human
consciousness present in individuals is what projects the
potential to the actual. Thus, not only can Wigner's consciousness project
the cat's state, but Schrödinger or any other person can as
well. This solution not only solves the problem of
projection, but it also prevents Schrödinger from existing in
a potential state—a proposition which Wigner just could not
tolerate. But Wigner's restriction of this consciousness to
human individuals has serious faults.

The first problem with Wigner's approach is that it gives
an unexplained special status to human consciousness.
Why is it that a human consciousness can make
the cat actual but a monkey consciousness can not? And if we give
consciousness to monkeys, then why not give it to cats? And then
what about mice? How about insects? Where do we draw the
line? And if we allow consciousness to go all the way down to the particles
themselves, they would continually observe themselves, and never exist
in potentia at all, contradicting experimental evidence. And even if we were able to
draw a clear line somewhere between human consciousness
and animal consciousness, at what age does a human suddenly
have the ability to actualize cats? At ten? At two months?
At birth? As a fetus? At conception? The development of an organism is a
matter of degree, while the projection from potential to actual is
not. This solution is thus very arbitrary, and is
reminiscent of the idea that things become actual when they
get big enough; only instead of size, Wigner has chosen
"human consciousness" to be the property which determines
when the world becomes actual. Considered as an observable
property of biological organisms, the term "human
consciousness" is both ambiguous and problematic. It is not surprising, then,
that many physicists have rejected Wigner's proposal and looked for other explanations
of the measurement problem. After decades, however, the problem still remains unsolved.

To illuminate the problems with Wigner's proposal, let us
look at his argument for making human consciousness special. "O.K.",
Wigner says, "suppose Schrödinger was in a potential state
before I looked at him. Now, after I look at him I ask
Schrödinger what he felt before I looked at him. Surely he
will not say that he was in a potential state! Thus," Wigner
concludes, "Schrödinger must have been in an actual state
before I looked at him." As convincing as this may sound,
Wigner's argument proves nothing. Suppose we replaced
Schrödinger with a sophisticated robot. The robot would
never say it was in a superposition either, for when Wigner
looks at it, the robot will actualize into a state which had
recorded either a live cat or a dead cat. Similarly, when
Wigner looks at Schrödinger, Schrödinger will actualize into
a state "Schrödinger with the memory of having seen a live
cat" or "Schrödinger with the memory of having seen a
dead
cat." So there is no evidence that Schrödinger
is any different than a robot or a cat. After all, as far
as Wigner is concerned, Schrödinger's body and brain are made
of atoms just like the radioactive atom, all of which will be
in potential states until Wigner looks at them.

Wigner made the mistake of objectifying the subject: he gave
a material object (Schrödinger's body) the property of a
conscious subject. Wigner has no
way of knowing for certain that Schrödinger is ever conscious
of anything, and so he has no basis for the claim that
Schrödinger or any other human is responsible for the
projection from potentiality to actuality. Wigner's claim is
just as arbitrary and unverifiable as the claim that big
objects are responsible for the projection. This type of ambiguity
is one reason many physicists object to bringing consciousness into
physics as Wigner proposed.

Yet, despite this problem with Wigner's proposal, he can still
be absolutely certain of one thing: While Wigner can never know
if anyone else is conscious, he can be certain that he
is. Strictly speaking, Wigner has absolute certainty regarding the
existence of just one consciousness, namely, 'his' consciousness.
For Wigner, the only time
he can be absolutely sure that a potentiality has become an
actuality is when a definite measurement result appears in his consciousness. But
Wigner was repulsed by this denial of other people's
existence, and understandably so: This all seems to imply
solipsism, the view that he is the only subject, that he is
the only conscious being and everyone else is just an object,
like robots or machines, in his consciousness. Furthermore,
this same argument would apply to each of us: The only
conscious subject that you can be certain of is yourself.
Your consciousness is responsible for the projection from
potential to actual.

Thus, to correct Wigner's mistake of
objectifying the subject, of arbitrarily granting
consciousness to objects, we are apparently forced to accept
solipsism: for you, there is no certainty that anything
exists but yourself and your world. And for Wigner, the only
certainty is himself and the existence of his world. So, are there
millions of fragmented people experiencing
their own personal worlds with no apparent connection between
them? A world for you, a world for me, a world for Wigner?
Yet the only world you can be certain of is your own.

The first problem that results from this situation is related
to the identification of conscious subjects. In your world you will be
claiming to be the true subject responsible for making the
world actual, while other people will be arguing that, in
fact, each of them is the observer of the world and you are
just an object in their consciousness. Yet you know they are
absolutely wrong. Thus we have a proliferation of conscious
subjects, each of whom claims to be the one and only subject—
hence the unresolvable arguments over who is responsible for
whose existence.

The problem at the root of all this lies with the fact that
solipsism does not completely eliminate the objectification of
the subject. We get stuck in solipsism only because we are
still making consciousness a property of our mind-body when,
in fact, our own body, thoughts, and feelings are all objects
appearing in consciousness. The conscious subject can
not "belong" to any object, and that includes our thoughts and bodies
as well as other humans such
as Wigner and Schrödinger. Just as it is a mistake to attribute consciousness to objects such as Schrödinger and other people,
it is also a mistake to attribute consciousness to the objects
which comprise our own mind and body! All we can say for
sure is that there is consciousness, and that the entire world of experience, including our own inner thoughts and feelings, appears
in it.

Once this last objectification of the subject is recognized,
we have solved the first problem, because we can no longer
claim that other people are just objects in "our" personal
consciousness. Now we are just an object in consciousness,
too. And everyone will agree with us on this point. "Yes,"
they will each say, "there is a consciousness. This body and
these thoughts are in it, and everyone else is in it,
too." People can no longer argue, "you're just an object in
my consciousness." Not because other people are not objects
in consciousness, but because there is no "my" consciousness anymore.

At this point something amazing happens. What reason is
there to think that the consciousness in which one person's
world appears is different from the consciousness in which
another person's world appears? Each unique person has a unique world
that arises relative to their perspective. But the both the person and the world
arise together to the subject, to consciousness itself. Is the subject to Wigner's
world separate from the subject to Schrödinger's world?
Consider what it would be like to switch places with a friend
of yours, say Wigner. To just switch bodies, but not brains,
would give you a good idea, but you would still not really
know what it would be like to be Wigner unless you switched
brains too. After all, even if you could be in his body, you
still would not have his memories and skills that would allow
you to truly experience what it is like to be Wigner in his
essence. So you decide to switch places completely—body,
brain, memories, everything. But to really know what it is
like to be him, you must leave behind your own memories, for
part of what makes Wigner unique is the fact that he does not
have your memories. So you make this pure switch, and you
live as Wigner for a day or two, then you switch back. But
since none of the memories were switched, when you get back,
it will be as if you had never switched at all! When you are
Wigner, you would not know it and when you got back, you
would not know you had been gone. So you could be switching
back and forth all the time, repeatedly throughout the day,
and your mind-body would never know it, "you" would never
know it. But if that is the case, then what is the real
difference between "your" consciousness and "Wigner's" consciousness? In your true
essence, you are your friend. It is only one consciousness,
one subject, that sees both worlds. Consciousness is not tied to any particular
person or object whatsoever.

Therefore, the mistake that leads to solipsism is the
objectification of the subject, or taking consciousness to be
tied to a particular mind-body. In fact, the mind-body is a
collection of objects in consciousness. The idea of separate
conscious individuals is thus an illusion resulting from not
recognizing this fact. As Schrödinger himself wrote,
"the plurality that we perceive is only an appearance; it is
not real." In fact, there is just one conscious subject, and
you are that.

Although we have resolved the problem caused by the
proliferation of subjects, we have still to solve another
problem. This second problem is related to the fragmented
worlds of which this subject is conscious. How are these separate
experienced worlds integrated to give rise to a shared, objective
world? In fact, we hardly need quantum mechanical paradoxes
to see that this is a problem. After all, do not all
individuals live in their own separate worlds, experiencing
life from the particular point of view of one body, living in
a certain culture during a certain time period? Certainly
you see different things from Wigner, you experience
different things from your friend. Even if you are both
looking at the same object, you still see it from different
angles and experience different reactions. Strictly
speaking, no two people live in the same experiential world.
Consequently, the notion of an objective world—that we
actually experience the same world "out there"—becomes
questionable. While we can say that it is as if there were
an objective, shared world, in fact, we each experience our
own personal world of phenomena. In this case, the whole
quest of science to discover the laws of an objective world
"out there" seems to be nothing more than a useful abstraction.
All that is directly experienced are the various
worlds of experience.
And even if there is one subject common to the worlds, it still seems as if there are
separate worlds, each centered around a particular mind-body.
One world appears relative to your mind-body, while a totally
different world appears relative to Wigner's mind-body.
Thus, we still have a serious problem dealing with
objectivity.

While it may seem that objectivity is totally lost, it has only taken a new form.
To understand
what has happened to objectivity, it is
useful to draw an analogy with Einstein's special theory of
relativity. Einstein's theory showed two important things.
First, all measurements of time and space are relative—they
depend on the point of view, or reference frame, of the
observer. Second, the laws of nature do not depend on the
point of view—all worlds are governed by the same laws.
Thus, while the way nature appears to each mind-body depends
on its point of view, the laws of nature do not. Objectivity
no longer applies to the separate worlds of appearances. It
only applies to the common laws behind them.

Niels Bohr, the father of the quantum revolution, wrote that
a study of these two revolutionary theories of the 20th
century "reveals striking similarities as regards the
renunciation of the absolute significance of conventional
physical attributes of objects." So, he says, "[we must use
the word] phenomena exclusively to refer to the observations
obtained under specified circumstances." In other words, the
phenomenal world that appears to each of us is not objective,
or absolute, but relative. To talk of the "actual" state of
an object without reference to an observer in quantum
mechanics is meaningless, just as is talking about the
"actual" length of a time interval without reference to an
observer in relativity. The "actual" world you experience is
just a particular projection of the world of
potentiality, like shadows flickering on the walls of a cave.
And the particular appearance of the shadows will depend on
the position of the light, on your point of view.

In addition, just as there is no preferred reference frame in
relativity, there is no point of view that is more special
than any other. While the apparent world that manifests in
your reference frame is a different world of appearance altogether from the
world that manifests in the reference frame of your friend,
both are fundamentally just as valid. While all points of
view are created equal, they still are unique
expressions of the world. Just as the shadow of an object
cast by a light from one angle is no more true or false than
a shadow cast by a light from another angle, no one person's
point of view is ultimately any more true or false than
another's.

But quantum mechanics differs from relativity in one
important way: the objects casting the shadows are not
actual but potential. There is an objective world, but it is
not an actual world fixed in space and time. The
objective reality described by quantum theory is a potential world of possibility, beyond
this shadow-play of spatio-temporal appearances we call
actual. Furthermore, that objective world of potentiality is
nonseparable—even though it decoheres into apparently separate worlds,
it is in a deeper sense a single object, just as we
have found that there is just a single subject. But out of
this pair are manifested many relative worlds appearing to
different people in different places at different times. And
from the different relative worlds, each mind-body never sees
the whole potential reality but only a limited, actualized
projection from one unique point of view. In Schrödinger's
words, "this whole is not so constituted that it can be
surveyed in one single glance." But behind this apparent
proliferation of subjects and objects, all are united and
intricately interconnected.

Thus, we have now revealed beneath the veil of Newton's
universe a quantum realm of reality in which objects cannot
exist alone, independent of a conscious subject. And while
the one unitive subject is free of the limitations of any
particular point of view, what becomes actual in each world
depends on the observer at the center of that world, the
individual mind-body who defines the reference point for that
relative world. And there are as many relative worlds as
reference points to be chosen. A world for you, a world for
your friend, a world for every plant and every animal, and
even a world for the stars and planets and every single atom.
Yet, in a deep and profound sense, these worlds are merely
different projections of a single potential reality common to
them all, a nonseparable reality interweaving them all into a
coherent whole and its archetypal Law, making objectivity and
science possible. And at the center of each relative world
is the one subject, uniting the worlds from the subjective
side and making human relationships meaningful.

And so we lose our last remaining link to the old cosmic
machine. We have pierced completely through the illusion of
Newton's world and have discovered the strange and wonderful
world of the quantum, a world that is right here and now,
veiled beneath the apparent reality of matter, determinism,
naive objectivity, and separation. The world is not made of
hard matter. The world of appearance does not strictly follow
deterministic laws. The world is not just a collection of
separate parts. The properties of objects do not exist independent of observers. No, the world
is not what we have thought it to be after all. Beneath this
illusion lies a quantum realm where strange and wonderful
things can happen. And this quantum wonderland is not some
far off place, it is not some fiction. This is the world
right here and now, a world that modern physics has lead us
to.

Implications: Life In The Quantum Realm

Finally, we have found our way to the quantum realm, a world
of possibility and spontaneity, a world of unbroken unity.
This quantum reality we have found at the end of our journey
is composed of a Subject and an Object. The Subject is the
One source of conscious awareness which shines forth through
the Many individuals. The Object is the One potential for
the appearance of the Many phenomenal appearances in all the
individual worlds.

Being such a profound change in our world view, what
implications does this quantum reality hold for us? The most profound
changes are not the changes to the world, but the
changes in how we see the world. The discovery of quantum mechanics
has opened up a vast new quantum world that can free us from
an outdated world view and its illusions of separation and
materialism. Going far beyond superficial technological
changes, the quantum world has the potential to transform the
basis of our individual and social actions. By recognizing
the essential identity of oneself with other creatures, one
acts from unity and compassion rather than separation and
conflict. Kindness to others is kindness to oneself and
cruelty to others is cruelty to oneself. In addition, by
acknowledging the unity of all creatures, a common ground is
established beneath the political, ideological, and cultural
divisions at the root of so many world problems. In the
quantum world, separateness is only half the story. Beneath
all diversity is a unity.

So, let us
follow the vision of these heroic adventurers to the quantum
realm. The new world has been discovered. Now it awaits
those who are called to leave the old lands and seek beyond.
It awaits us.

2017 Postscript

It should be emphasized that the above exposition provides an interpretation
of quantum mechanics, a way of understanding the world described by the mathematical formalism of the theory.
There are other interpretations of quantum mechanics that also provide valid ways
of understanding what kind of world the theory describes. Interpretations do not differ
in their empirical content, and neither the theory nor experiment uniquely determine
any one interpretation. We are free to choose.
How we choose to understand the world, however, has consequences.